#include<stdio.h>
long  f(int  g){
    switch(g){
        case 0:return 0;
        case 1:
        case 2:return 1;
    }
    return (f(g-1)+f(g+2));
}
int main()
{
    long k;
    k=f(7);
    printf("k=%d\n",k);
    return 0;
}